Brief Description of the Prior Art
It is known to provide dimmer switches which control the power to a load by the use of a variable resistance or rotary potentiometer. In some of these dimmer switches, the variable resistance is operated by the use of a pivoted lever, toggle or pivoted operating handle. A structure of this general type is shown in West German Pat. No. 3,144,794 issued in 1981, and is used for dimming the panel lights of a motor vehicle. The dimmer switch employs a drive train between an externally protruding thumbwheel, manipulated by the vehicle operator for dimming the panel lights, and a rotating slide wiper of a rheostat which controls the current flow to the panel lights. The drive train includes a toothed gear segment which engages a pinion gear carried on the shaft of the rheostat. The gear segment is carried on a pivoted element which has a forked end. The slot at the forked end engages a peg carried on the side of the thumbwheel. As the thumbwheel is rotated, the peg moves in the slot to cause the forked element to swing or pivot, thereby translating the gear segment to drive the pinion wheel of the rheostat. This system makes no provision for adjusting the extent of engagement of the teeth on the gear segment with the teeth on the pinion wheel. This relationship is fixed.
U.S. Pat. No. 3,958,087 discloses a switching device which is operated by manipulation of a lever which protrudes from the switch housing, and is operatively connected to a rotatable, indicia carrying switch wheel. A gear segment is provided which meshes with a pinion gear carried on the switch wheel, so that as the gear segment is pivoted by pivotation of a projecting switch lever, the pinion wheel is caused to undergo rotation through a relatively large angle. U.S. Pat. No. 3,958,087 indicates that the toggle or lever portion of the disclosed switch can replace the thumbwheel used in certain types of prior art switching devices. As in German Pat. No. 3,144,794, however, the structure here described does not have any means for adjusting the degree of engagement of the gear segment with the pinion which it drives so as to provide a smooth, trouble-free action between the toggle arm and the rotatable switch wheel. Moreover, switching is accomplished incrementally by a series of discrete, intermittently engaging wiper contacts.
In the structure disclosed in U.S. Pat. No. 3,949,347, a rotary potentiometer is utilized to variably control the voltage to a load. The control circuit is mounted on a printed circuit plate. This dimmer switch is connected into a conventional three-way switching unit. The rotary potentiometer is in a conventional current control circuit for controlling the delay firing angle of a triac which is connected in series with the load.
U.S. Pat. No. 4,117,445 is directed to a rheostat or potentiometer which includes a resistive substrate across which a wiper is translated in response to the pivoting action of a toggle or pivot lever projecting from the housing in which the switch is located. A printed circuit board supports the resistive substrate and other circuit elements. The toggle lever does not function to drive the shaft of a rotary variable resistance.
Another type of toggle dimmer switch which mounts in an electrical wall box and employs a pivoted toggle or lever to cause a wiper to slide across a resistive contact element is disclosed in U.S. Pat. No. 3,310,768. The operating lever is preferably molded from an insulating material, and has integrally formed trunnions extending from a body portion in opposite directions. The trunnions are seated in trunnion seats in order to permit the operating member to be pivoted as a lever. A printed circuit board is employed for mounting the circuit components of the system.
In U.S. Pat. No. 3,990,033 issued in 1976, an electric power controller is disclosed in which conductive and resistive tracks are mounted in a common plate on a common circuit board, along with normally open and normally closed contact devices. The entire assembly is housed within a protective housing of insulating material. The conductive and resistive tracks mounted on the circuit board are contacted by a flexible bridging contact element which is carried on an arm of an internal controller member. The controller member includes a pivot shaft pivotally supported by the walls of the housing, and a manual control lever which projects through a slot in a mounting plate secured to, and covering, the open side of a protective housing. The actuator arm carries a flexible bridging contact element for sliding engagement with the conductive and resistive tracks. The circuitry does not employ a rotary variable resistor.
U.S. Pat. No. 4,085,399 issued in 1978 and assigned to Power Controls Corporation, discloses a pivoted power controller which, in its limit positions, engages a switch operating element to close or to open the power control circuit through switch contacts mounted on a circuit board enclosed within a housing. A resistive element mounted in the circuit and on the circuit board is engaged by a wiper on the controller during travel of the wiper between its limit positions. The power supplied to a load is thus varied. The wiper is actuated by means of a toggle arm or pivoted lever which projects through an opening in one side of the housing. The manual lever or toggle arm is pivotally mounted by means of trunnion shafts. In this switching structure, no rotary variable resistance is utilized.